Fuel filtering and heater combination



July 9, 1963 w. KASTEN FUEL FILTERING AND HEATER COMBINATION 3Sheets-Sheet 1 Filed Oct. 26, 1959 Ill/l/I/II INVENTOR. WHL 72 164575ATTOIPA/E) July 9, 1963 w. KASTEN 3,097,155

FUEL FILTERING AND HEATER COMBINATION Filed Oct. 26, 1959 s Sheets-Sheet:s

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j 1 E 1 U INVENTOR.

W41 72" K4575 BY W 1% 3,097,165 Patented July 9, 1963 3 097 165 FUELFILTERING AhlD IIEATER COMBINATION Waiter Kasten, Madison Heights, Michassignor to The Bendix Corporation, South Bend, Inch, a corporation ofDelaware Filed Oct. 26, 1959, Ser. No. 848,559 8 Claims. (Cl. 210-133)The present invention relates to fuel filtering and heater devices ofthe type disclosed in my copending application Serial No, 814,617, andmore particularly to certain improvements relating thereto.

One of the Objects of this invention is to provide a single unit whichfunctions as a filter deicer, fuel filter, fuel heater and lube oilcooler.

Another object of this invention is to provide a single unit of the typedescribed wherein lube oil is utilized as the primary heat source andcompressor bleed air is utilized as an auxiliary heat source.

A further object of this invention is to provide a single unit of thetype described which incorporates a Single or a plurality of safetychambers for preventing intermixing of oil, air and/or fuel in case ofleaky brazed joints.

A still further object of this invention is to provide a head castingfor a single unit of the type described which includes all of thenecessary inlet and outlet passages and requisite partition meanstherebctwcen for the fuel, oil, and air passing through said unit.

An important object of this invention is to provide a single unit of thetype described incorporating a by-pass valve arrangement which permitscontinued flow of fuel along the complete length of the heat transfermeans, located within the filter elements, under clogged filteringconditions.

An additional object of this invention is to provide means on thedownstream side of each filter element which will divide the fuel intorelatively thin streams, so that heat may be transferred thereto in amore efiective manner.

A further object of this invention is to provide a fluted filter elementsupport which will aid in extending the service life of the associatedfilter element.

Other objects and advantages will become apparent from the followingdescription and accompanying drawings, wherein:

FIGURE 1 is a view in partial section of one embodiment incorporating myinvention;

FIGURE 2 is a sectional view taken along line 2-2 of FIGURE 1, showingonly one set of heater tubes within a filter element;

FIGURE 3 is a sectional view of a portion of another embodimentincorporating my invention;

FIGURE 4 is a sectional view of a portion of a further embodimentincorporating my invention;

FIGURE 5 is a sectional view taken along line 5-5 of FIGURE 4;

FIGURE 6 is a sectional view of a portion of a still further embodimentincorporating my invention;

FIGURE 7 is a sectional view taken substantially along line 7-7 ofFIGURE 6;

FIGURE 8 is an enlarged view partially in section with portions brokenaway for clarity of a single filtering element and the heat transfermeans located therein;

FIGURE 9 is a sectional view taken along line 9-9 of FIGURE 8;

FiGURE 10 is an enlarged sectional view of a portion of a flexiblefilter element and its fluted support member; and

FIGURE 11 is a view similar to FIGURE 10 showing the filter element in aflexed position.

Referring to FIGURES 1 and 2 of the drawings, it will be noted that myfuel filtering and heater device includes a head 10 having a pluralityof annular chambers 12, 14, 16, 18 and 20 formed therein. Chambers 12and 14 communicate with lube oil inlet and outlet ports 22 and 24,respectively, while chambers 16 and 18 communicate with compressor bleedair inlet and outlet ports 26 and 28, respectively. Safety chamber 20communicates with a leak detector port 30'. A fuel bowl 32 is suitablyconnected to head 10 through means of a bolt 33 and forms a fuel chamber34 therewith which communicates with fuel inlet and outlet ports 36 and38. Located in fuel chamber 34 and interposed between the fuel inlet andoutlet ports 36 and 38 is a retainer plate 40 which is held in positionby a spring 42. A plurality of filter elements 44 are suitably connectedto retainer plate 40 and are arranged in inner and outer concentricrings. These filter elements may consist of tubular screens, wire woundelements, ribbon elements or any other types of elements havingreasonably good conductivity which could be made in a wrap-around orsubstantially cylindrical unit and attached to the retainer plate 40.Each of the filter elements contains a lay-pass valve 46 at the lowerend thereof for purposes to be subsequently explained. Located withinand in contact with each of the filter element of the outer ring are aplurality of U-shaped tubes 48 each of which has one end communicatingwith oil inlet chamber 12 and the other end communicating with oiloutlet chamber 14. A plurality of U-shaped tubes 59 are similarlylocated within and in contact with each of the filter elements 44 of theinner ring, but each of these tubes has one end communicating with airinlet chamber 16 and the other end communicating with air outlet chamber18. The tubes 48 and 50 may be formed of any suitable noncorrosivematerial having relatively high conductivity and may be nested in setsof two, three or more pairs, as desired. A water drain plug 52. isprovided for removal of any free water that may accumulate in the bottomof the bowl.

Operation of the device is as follows: Hot lube oil enters chamber 12through inlet port 22, fiows through the U-shaped tubes 48 in the outerring into chamber 14 and leaves the device via outlet port 24. The fuelto be filtered enters the fuel inlet port 36, flows through the filterelements 44 from the outside to the inside and leaves the unit via fueloutlet port 38. Any contaminants in the fuel will be deposited on theoutside of the filter media and can be readily removed by back-flushingor cleaning. Since the U-shaped tubes 48 are physically in contact withthe filter elements 44, heat from the hot lube oil will be transferreddirectly to the filter surfaces, through means of conduction, to preventpossible clogging of the filter elements by formation of ice thereon.Since the fuel, once inside of the filter elements, must fiow along theheater tubes 48, the fuel will be heated to a temperature about +32 F.and the oil will be cooled. It has been found, however, that lube oildoes not normally contain sufiicient heat to heat the fuel under allflight conditions, For example, at the initial start of a flight, thefuel is still fairly warm and very little heat is required, but duringvery long flights at high altitudes, when the fuel may have cooled to-50 F. or lower and the engines are throttled back to cruising, the lubeoil does not get hot enough to bring the fuel above +32 F. In order toobviate this difficulty additional heat is provided by utilizingcompressor bleed air as a second heat source. Thus, hot compress-orbleed air enters chamber 16 through inlet port 26, flows through theU-shaped tubes 50' of the inner ring into chamber 8 and leaves thedevice via outlet port 28. Heat is transferred from the inner ring ofheater tubes 50 to the filter elements 44 and the fuel flowingtherealong in the same manner as that described with respect to theheater tubes 48 in the outer ring. Thus, the outer ring of heat transfertubes and filter elements constitutes a filter deicer-fuel filter-oilcooler-fuel heater combination, and the inner ring which utilizescompressor bleed air as auxiliary heat is essentially only a filterdeicer-fuel filter-fuel heater combination. Since one of the purposes ofmy unit is to cool the lube oil flowing through tubes 48, such lube oilwill flow therethrough continuously. But, since heat may not be requiredat all times through inner U-shaped tubes 50, flow of compressor bleedair therethrough may be controlled by any suitable means, so that flowtherehrough will be intermittent in any predetermined desired manner.

In order that the unit will always remain effective as an oil cooler, Ihave utilized individual by-pass valves 46 in the bottom of each filterelement 44 so that if any filter clogging occurs, fuel will enter thebottom of the filters and flow past the complete length of the heattransfer tubes to cool the oil flowing therethrough. By o locating theby-pass valves, it will be obvious that heat exchange will always occurbetween the fuel and the oil regardless of the condition of the filterelements.

Since the weakest part of most conventional heat exchangers is thebrazed joints where the heat transfer tubes are attached to the housing,any fractures and subsequent leakage will leak fuel into the oil coolersection and cause fire or engine failure. In my proposed arrangement,this danger has been eliminated by interposing a separate safety chamberbetween the fuel section and the oil compressor bleed air compartments.This safety chamber is vented to the atmosphere via port or may beconnected to an expansion chamber having a pressure sensing valve (notshown) for detecting leaks.

The FIGURE 3 embodiment is essentially the same as that of FIGURE 1except that the filter elements 44 are now open at both ends and areequipped with an additional retainer plate 54 at the lower end thereof.Furthermore, the multiple by-pass valves 46 of FIGURE 1 have beenreplaced by a single by-pass valve 56 in the lower retainer plate 54which will permit, during clogged filtering conditions, flow of fuelfrom the fuel inlet port 36 to the lower open end of the filter elements44, via a plurality of openings 58 located in a cylindrical extension60, of the lower retainer plate 54. Thus, flow will be from one open endof the filter elements to the other open end.

Referring to FIGURES 4 and 5, it will be noted that i this embodiment issimilar to the embodiment shown in FIGURE 3, except that an additionalsafety chamber 62 has been added for preventing intermixing of thevarious fluids in the event that one of the thin small diameter heattransfer tubes 48, 50 breaks. transfer from the tubes 48, 50 to the fuelis improved by attaching hollow externally fluted cylinders 64 to thehead so that one end of each cylinder opens into chamber 62. The otherend of each cylinder 64 is closed. The arrangement is such that thefluted cylinders 64 surround and are in contact with the heat transfertubes 48, 50, and are in turn surrounded by the filter elements 44. Thehollow portion of the fluted cylinder is filled with metallic sodium(suitably sealed therein) which serves as an effective heat transfermedium between the heater tubes and the filter elements. The fins 66formed on the external surface of the fluted cylinder (see FIGURE 5) arein intimate contact with the filter elements, so that after the fuel haspassed through the filter elements it will flow along the outer grooves68 formed by the fins. In this manner the fuel is divided into very thinstreams which are surrounded by metal so that heat to be transferredfrom the heating media can be transferred to the fuel without having togo through a large mass of fuel. It will be noted that there is nodirect connection between the outside of the heat transfer tubes and thefuel chamber. If, for any reason, one of the small heater tubes shouldbreak, oil or air pressure will build up in the chamber 62. A pressuresensitive device (not shown) if con- In addition heat 4 nected to thischamber, could be used to shut off the oil or bleed air supply to theunit and prevent further damage.

Another feature of the fluted cylinders 64 is that an automaticself-cleaning characteristic results when the cylinders are utilized inconjunction with flexible filter elements such as those made of metalscreen. During the early service life of the filter elements, when theouter surface of the elements is relatively free of contaminants, theflexible filter element 44 will maintain a position relative to thecylinders 64, as shown in FIGURE 10. If we assume that under a given setof conditions of fuel flow, the pressure loss through the filter elementis 1 p.s.i., then We may have an external pressure (outside the filterelement) of 2 p.s.i. and an internal pressure (inside the screen) of 1p.s.i. As solids accumulate on the external surface of the filterelement the pressure drop thereacross will gradually increase to a pointat which the filter element will flex inwardly between fins 60, as shownin FIGURE 11. Such a flexing may occur, for the same given flowconditions, when the external pressure reaches 4 p.s.i. while theinternal pressure remains at l p.s.i. Any further increase in thepressure differential would normally open the by-pass valve meansassociated with the particular filter element. If we assume that thebypass valve is set at a 4 p.s.i. differential pressure, it will opensoon after the differential pressure exceeds 4 p.s.i. The moment thishappens the pressure inside of the flexible filtering element will riseabove the l p.s.i. value and since the dynamic head approximates thestatic head the by-pass valve will remain open even though the externalfilter pressure is reduced to less than 4 p.s.i. This occurrence reducesthe external load on the filter elements and increases the pressureinside of the tubes thereby causing a flexure of the screen elements inreverse. This reverse flexing dislodges some of the contaminants so thatnormal filtering action re-occurs and the by-pass valve returns to itsclosed position. As a result of this self purging action the effectivefiltering life of the element is increased considerably.

Referring to FIGURES 6, 7, 8 and 9, it will be seen that this embodimentis essentially the same as that shown in FIGURE 4, except that thesafety and sodium chambers have been eliminated and the heating mediumis carried directly inside of the fluted cylinders 64, which previouslycontained the small heater tubes 43, and the sodium as the heat exchangemedium. These fluted cylinders are now provided with an insert 70 havingradial spokes extending from the center thereof. Basically this insertserves the purpose of directing the flow of the heat transfer mediumfrom the open end of the hollow externally fluted cylinder 64 to theclosed end thereof over substantially one-half of the effective area ofthe tube. After it reaches the closed end of the cylinder, the how isreversed and it passes along the other half of the cylinder to the openend. Therefore, it is necessary that the insert be spaced from thebottom end of the fluted cylinder 64 by approximately a distance equalto the diameter of the cylinder. The fuel to be heated flows through thefilter elements 44 and along the grooves 68 formed on the flutedcylinder 64 and thence to the fuel outlet port. The FIGURE 5 embodimentalso uses the single by-pass valve 56 which permits flow from one openend of each filter element, along grooves 68 and out the opposite openend in a manner previously described when clogged filtering conditionsoccur.

The several practical advantages which flow from my invention arebelieved to be obvious from the above description, and other advantagesmay suggest themselves to those who are familiar with the art to whichthis invention relates.

Having thus described the various features of the invention, what Iclaim as new and desire to secure by Letters Patent is:

1. A fluid filtering and heater device comprising a head having a firstchamber formed therein communicating with a first inlet port forpermitting ingress of a first fluid, a second chamber formed thereincommunicating with a first outlet port for permitting egress of saidfirst fluid, a third chamber formed therein communicating with a secondinlet port for permitting ingress of a second fluid, and a fourthchamber formed therein communicating with a second outlet port forpermitting egress of said second fluid, a bowl operatively connected tosaid head and forming a fifth chamber therewith, said fifth chambercommunicating with a third inlet port and a third outlet port forpermitting ingress and egress of a third fluid, a retainer plate locatedin said fifth chamber and interposed between said third inlet and outletports, a plurality of tubular members operatively connected to said headand extending through said retainer plate, said tubular members eachhaving two separated openings located therein, some of said tubularmembers having one of said openings communicating with said firstchamber and the other of said openings communicating with said secondchamber and others of said tubular members having one of said openingscommunicating with said third chamber and the other of said openingscommunicating with said fourth chamber, a plurality of filter elementsof the outside-in type operatively connected to said retainer plate forfiltering the third fluid flowing from said third inlet port to saidthird outlet port, said filter elements each surrounding one of saidtubular members and being in contact therewith, and by-pass meansinterposed between the third inlet port and the downstream side of saidfilter elements for permitting continued flow of said third fluid insideof said filter and along said tubular members under clogged filteringconditions.

2. A fluid filtering and heater device as defined in claim 1 wherein asafety chamber is formed in said head and is located between the fifthchamber and the remaining chambers for insuring against intermixing ofsaid various fluids.

3. A fluid filtering and heater device as defined in claim 1 wherein aplurality of safety chambers are formed in said head and are locatedbetween the fifth chamber and the remaining chambers for insuringagainst intermixing of said various fluids.

4. A fluid filtering and heater device as defined in claim 1 whereinsaid by-pass means includes a plurality of bypass valves each of whichis operatively connected to only one of said filter elements and isfunctionally independent of the other by-pass valves.

5. A fluid filtering and heater device as defined in claim 1 whereinsaid by-pass means includes a single by-pass valve interposed betweensaid third inlet port and the downstream side of all of said filterelements.

6. A fluid filtering and heater device comprising a housing having afirst chamber formed therein communicating with a first inlet port forpermitting ingress of a first fluid, a second chamber formed thereincommunicating with a first outlet port for permitting egress of saidfirst fluid, a third chamber formed therein for communieating with asecond inlet port and a second outlet port for permitting ingress andegress of a second fluid, partition means for separating said chambersfrom each other, means located in said third chamber and interposedbetween said second inlet and outlet ports for filtering the fluidflowing therebetween, said last named means including a pair of retainerplates and a plurality of porous filter tubes of good conductivity andof the outside-in type having the opposite ends thereof opening throughsaid retainer plates, a plurality of hollow non-porous externally flutedmembers operatively connected to said housing, one of which is locatedwithin and in contact with a substantial portion of the length of eachof said filter tubes for transferring heat thereto and to the secondfluid flowing along said fluted members on the inside of said filtertubes to thereby prevent the formation of ice on the filter tubes and inthe second fluid flowing through said filter tubes, said fluted memberseach having an open end and a closed end, means operatively connected tosaid housing and located within the hollow portion of each of saidfluted members for forming two separated openings and a flow paththerebetween, one of said openings communieating with said first chamberand the other of said openings communicating with said second chamber,and bypass valve means interposed between the second inlet port and thedownstream side of said filter tubes for permitting continued flow ofsaid second fluid along the external surface of said fluted membersunder clogged filtering conditions.

7. A fluid filtering and heater device as defined in claim 6 wherein themeans operatively connected to said housing and located within thehollow portion of each of said fluted members comprises an insert havingradially extending spokes in contact with the hollow portion of saidfluted member, said insert being spaced from the closed end of saidfluted member.

8. A fluid filtering and heater device as defined in claim 6 whereinsaid porous filter tube is formed of a material capable of flexing intothe flutes of said fluted member as a result of variations in thedifferential pressures acting thereacross to thereby provide aself-cleaning action.

References Cited in the file of this patent UNITED STATES PATENTS654,592 Barr July 13, 1900 813,918 Schmitz Feb. 27, 1906 1,075,978Joerin et al Oct. 14, 1913 1,856,771 L-oefller May 3, 1932 2,057,932Bolser Oct. 20, 1936 2,183,616 Korte Dec. 19, 1939 2,212,932 FairlieAug. 27, 1940 2,300,849 Tauch Nov. 3, 1942 FOREIGN PATENTS 12,539 GreatBritain June 2, 1904 70,805 Netherlands Aug. 16, 1952

6. A FLUID FILTERING AND HEATER DEVICE COMPRISING A HOUSING HAVING AFIRST CHAMBER FORMED THEREIN COMMUNICATING WITH A FIRST INLET PORT FORPERMITTING INGRESS OF A FIRST FLUID, A SECOND CHAMBER FORMED THEREINCOMMUNICATING WITH A FIRST OUTLET PORT FOR PERMITTING EGRESS OF SAIDFIRST FLUID, A THIRD CHAMBER FORMED THEREIN FOR COMMUNICATING WITH ASECOND INLET PORT AND A SECOND OUTLET PORT FOR PERMITTING INGRESS ANDEGRESS OF A SECOND FLUID, PARTITION MEANS FOR SEPARATING SAID CHAMBERSFROM EACH OTHER, MEANS LOCATED IN SAID THIRD CHAMBER AND INTERPOSEDBETWEEN SAID SECOND INLET AND OUTLET PORTS FILTERING THE FLUID FLOWINGTHEREBETWEEN, SAID LAST NAMED MEANS INCLUDING A PAIR OF RETAINER PLATESAND A PLURALITY OF POROUS FILTER TUBES OF GOOD CONDUCTIVITY AND OF THEOUTSIDE-IN TYPE HAVING THE OPPOSITE ENDS THEREOF OPENING THROUGH SAIDRETAINER PLATES, A PLURALITY OF HOLLOW NON-POROUS EXTERNALLY FLUTEDMEMBERS OPERATIVELY CONNECTED TO SAID HOUSING, ONE OF WHICH IS LOCATEDWITHIN AND IN CONTACT WITH A SUBSTANTIAL PORTION OF THE LENGTH OF EACHOF SAID FILTER TUBES FOR TRANSFERRING HEAT THERETO AND TO THE SECONDFLUID FLOWING ALONG SAID FLUTED MEMBERS ON THE INSIDE OF SAID FILTERTUBES TO THEREBY PREVENT THE FORMATION OF ICE ON THE FILTER TUBES AND INTHE SECOND FLUID FLOWING THROUGH SAID FILTER TUBES, SAID FLUTED MEMBERSEACH HAVING AN OPEN END AND A CLOSED END, MEANS OPERATIVELY CONNECTED TOSAID HOUSING AND LOCATED WITHIN THE HOLLOW PORTION OF EACHH OF SAIDFLUTED MEMBERS FOR FORMING TWO SPEARATED FLOW PATH THEREBETWEEN, ONE OFSAID OPENINGS COMMUNICATING WITH SAID FIRST CHAMBER AND THE OTHER OFSAID OPENINGS COMMUNICATING WITH SAID SECOND CHAMBER, AND BYPASS VALVEMEANS INTERPOSED BETWEEN THE SECOND INLET PORT AND THE DOWNSTREAM SIDEOF SAID FILTER FOR PERMITTING CONTINUED FLOW OF SAID SECOND FLUID ALONGTHE EXTERNAL SURFACE OF SAID FLUTED MEMBERS UNDER CLOGGED FILTERINGCONDITIONS.